We're eager and an hour early at Cairns Trinity Wharf for our three-night Great Barrier Reef cruise.

A fit young man in marine uniform greets us. "Hi, my name is Doug, and I'll be your captain." His informality is a surprise, but that's the Australian way. Doug grabs our luggage and carries it aboard the 35-metre, 730-tonne Coral Princess, a 50-passenger ship designed for tropical cruising.

The vessel looks spiffy despite her 20 years of service. There are upholstered cane chairs in the dining room and two lounge areas, one holding a topical library. Original maritime art graces the walls; there's a full bar and souvenir sales.

Our cabin is spacious, with two square "portholes," and the ship offers a range of accommodation. It's worth noting that, although staterooms on the upper decks cost more, they also roll more in lumpy seas.

We cast off just before noon, excited to be under way.

The aroma of freshly baked muffins and Anzac "bikkies" -- a cookie invented during the First World War by the moms of Australian and New Zealand soldiers fighting together --lures passengers into the dining room. We're the only North Americans among Australians, Brits and German-speaking Europeans.

Dive instructor Darron Strachan, a Sean Connery-like Scot who counts this as his 12th year on the Great Barrier Reef, demonstrates wearing life jackets and how to don snorkelling equipment.

An introductory scuba dive is offered and seven or eight keeners sign up for the briefing. Note to those who want to scuba dive: bring medical certification or you'll miss out like Paul did.

Wasting no time getting up close and personal with the warm water and reef creatures, we moor off Thetford Reef just inside the outer Great Barrier Reef by mid-afternoon.

Marine biologist Alana Hazel starts off with a fish-feeding. She jumps in surprise as a two-metre blue Maori

Wrasse races from the deep and almost grabs her hand while she's feeding colourful reef fish.

A glass-bottom boat tour over the colourful coral gardens whets our appetite for getting wet. The attentive crew notice a couple of older bodies having trouble descending the ladder wearing fins, so they help us onto the platform used for the excursion boat, then lower it so we can simply float off into the sea. Crew members yell encouragement, wanting us all to have a great experience.

And we do. We learn that you needn't swim far, just float over the edge of the reef and the fish will come to you. What a glorious sight!

After watching a dazzling sunset from the top deck, we're served a sumptuous seafood buffet, with Australian wines.

We anchor in the lee of an island for the night, and after a cooked breakfast of bacon, eggs, spaghetti and grilled tomato, we motor to Nathan Reef.

Here lie some of the most colourful coral gardens in the world and many of the 400 species can be seen from the glass-bottom boat.

This turns out to be the best snorkelling of our lives (we've been in Mexico, Thailand, Bermuda and Caribbean waters). The scuba novices, gently coaxed through their paces two at a time by Darron, surface, ecstatic about their experience.

Alana free-dives to "borrow" some amazing creatures from the deep for a touch tank. Some passengers are game enough to hug a huge sea cucumber, which looks like -- well, a pineapple. Colourful starfish, mobile mushroom corals and trochus shells are passed around and admired.

Soon we head to Dunk Island resort for a coastal rainforest walk. Some opt for an icy beer by the resort pool where Paul talks with Alana, a recent graduate of the University of Queensland, about the amazing Great Barrier Reef.

The first coral reefs started forming about 500 million years ago. "By comparison, the Great Barrier Reef is relatively new; its fossil coral just 3,500 years old," Alana tells Paul. "And the reef didn't start growing up until the end of the Ice Age raised sea levels 8,000 years ago."

The "GBR" as Aussies call it, parallels the Queensland coast for more than 2,500 kilometres. The largest World Heritage site on earth, it contains more than 2,900 individual reefs and 300 coral cays. It covers a total area of 345,000 square kilometres, but its future is in jeopardy.

"The Great Barrier Reef is a transient living thing, but global warming is speeding up its degeneration," says Alana.

"Coral bleaching, a complex biochemical reaction, is reversible if elevated water temperatures decline to normal (28-29 C) within a short period of time. Also, if overall temperatures don't rise too quickly, the micro-organisms can adapt."

Environmental pressures can cause them to change their physical attributes but it's difficult for scientists to tell whether the changes are genetic or caused by stress.

"Let's hope they will quickly evolve and be able to survive. But if conditions are too extreme here, perhaps the corals will be able to colonize new sites. Some corals are fast-growing, while others take a century to mature.

"It's hard to stop Mother Nature in her tracks, but we're also learning that scientists sometimes jump to conclusions, misjudging the situation."

Alana mentions the crown of thorns starfish, recently feared as a scourge of the entire coral reef, but now understood to be a phenomenon that comes and goes.

Dining at the captain's table, we learn that Captain Doug Wyness began on crayfish and ferry boats and was planning to be a chef, but studied for his marine papers on the side. Two years ago, he became a skipper with Coral Princess Cruises, starting on the Papua-New Guinea, Vanuatu and New Zealand runs. He loves his job and it shows.

Heading through Hinchinbrook Channel next morning, we get a lesson in mangrove ecology from Alana before mooring at "deserted" Pelorus Island for a barbecue lunch, cooked by the versatile Captain Doug. Kebobs of chicken, steak and kangaroo with several salads are washed down by Aussie beer, soft drinks or wine.

Snorkelling is great here and we spot giant clams three metres down among the corals, their "lips" in various shades of green, blue and purple. Energetic swimmers have a cannonball contest off a raft.

Our last morning on board dawns windy and rough, so the ride has what Darron calls "lumps, bumps and wobbles." And so do we -- few passengers opt for the hot breakfast. Then we change course for Townsville and the rolling drops sufficiently for us to pose for the obligatory group photo.

We're sad that our dream cruise has ended. But we have great memories, lots of photographs and, for a while at least, the "sea legs" we developed in the past few days.

If You Go

- Cairns is a popular international destination. Communities hugging white sand beaches offer laid-back, affordable accommodation, fine restaurants and shopping away from city bustle and are easily reached by public bus service. We liked the Argosy Apartments on Clifton Beach, argosycairns.com

- We enjoyed riding the Skyrail Rainforest Cableway over the trees to Kuranda, returning by heritage train, and a visit to the Daintree-Cape Tribulation Rainforest, including a cruise in search of crocodiles. Both days were arranged through Down Under Tours, www.downundertours.com

- August through mid-November offers the best weather, while the "wet," bringing high heat and humidity along with the odd cyclone, runs from mid-November through mid-April.

- Nasty box jellyfish are prevalent in the area between November and June, but major beaches have stinger nets within which it's safe to swim. Bottles of vinegar at beach stations offer emergency treatment in case of a sting.

- Dining costs 10 to 20 per cent more than in Canada, but many restaurants are BYO, which helps cut the bill. Consider buying breakfast items at a supermarket -- cooked breakfasts are expensive.

- Gasoline ("petrol" in Oz) costs about 30 per cent more than in Canada. Car rentals and accommodation costs are roughly equal after currency conversion.

- There are many day trips to the reef. Overnight cruises run for three, four or seven nights and tariffs range from $1,350AUD up. Tipping is customary at the end of the voyage.

Concerned about the continued degradation of the world's coral ecosystems, the broadly-based World Conservation Union has designated 2008 as the second International Year of the Reef.

Objectives:

- Strengthen awareness about the value of coral reefs and associated ecosystems

- Improve understanding of the critical threats to coral reefs and generate solutions

- Generate urgent action at all levels to develop and implement effective management strategies for conservation and sustainable use of these ecosystems.

Based in Gland, Switzerland, the World Conservation Union brings together 83 states, 111 government agencies, more than 800 non-government organizations, and some 10,000 scientists and experts from 148 countries in a unique worldwide partnership. Information at www.iucn.org

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